Industrial vehicles by design may be used for a wide range of uses, duty cycles, and applications. In some operating conditions, industrial vehicles may be infrequently used to transport materials only when needed, e.g., in response to the occasional received shipment of goods. In other types of operating conditions, industrial vehicles may be used nearly around the clock in multiple shifts, with the only substantial down-time occurring during routine or required maintenance. Further, industrial vehicles may be exposed to a variety of environmental conditions ranging from near freezing temperatures in certain types of food handling/storage facilities, to very hot weather when operating in desert-like conditions. Some types of industrial vehicles, such as forklift trucks, may be tasked with having to frequently lift and lower heavy loads in addition to being driven and operated in the above described conditions. All of these activities may result in significant temperature variation to the engine, transmission, and other related components of the industrial vehicle at various stages of operation based, at least in part, on the workload and/or duration of work being performed.
Regardless of environmental temperatures, an internal combustion or diesel powered engine is generally considered “cold” prior to being started, and may need to be turned on for a period of time (typically some number of seconds) before it comes up to a predetermined operating temperature. At the predetermined operating temperature, the engine may be considered capable of efficiently generating power and/or of efficiently combusting fuel in order to limit the amount of emissions produced by the engine. However, the environmental temperatures can significantly affect the amount of time required to bring the engine up to operating temperature, and as a result the ability to operate the vehicle may be delayed.
When additional power demands are placed on the engine, such as when lifting or pushing heavy loads, the vehicle cooling system may not be able to adequately keep the engine and/or transmission sufficiently cool at all times. In some instances, one or more modes of vehicle operation may be restricted or prohibited in the event of engine or transmission overheating, which also impacts the availability of the vehicle to perform work. If the vehicle operating temperature becomes too high or is kept at an elevated value for a prolonged period of time, significant damage to the engine and/or transmission system may occur, potentially taking the vehicle out of service for an extended time.
This application addresses these and other problems.